None. This is an examinable patent specification submitted for a filing receipt under Code Section 111 (a).
The prior art is best demonstrated by U.S. Pat. No. 4,537,140 to Baker (1985) which has at the bottom of the hopper, a reciprocating, sliding plate with a lip at its rear forming a pusher bar, the plate of which tends to vibrate the infed coal and the pusher, causing the coal to travel down an inclined fire grate. This configuration has no means, however, for accurate regulation of the amount of coal infed nor to break up or prevent the formation of clinkers. Pusher bars of variable reciprocating stroke are generally known. None, however, are designed to keep the bar from contact with the coal or its fine. With wet coal or fines and the gases emitted in the burning thereof, sulfuric and nitric acid are formed which attack the pusher particularly and also cause jamming and excessive wear.
A somewhat modified automatic coal stoker of Potts (U.S. Pat. No. 4,662,290 of May 5, 1987), which also employs a pusher assembly, operated by a cam assembly 64 which reciprocally shifts step-like protuberance 58. It provides an enshrouded pusher which is resistant to attack from such acids. The intermittent pusher assembly of the Potts patent is incorporated by reference here as an ancillary feature of the present invention. The state of the art in the Potts device (1986) includes the long-established perforations 32 of fire grate 30, which grate may be an integral member as depicted, or it may be composed of two or more grate modules that aid loading of the device. Common to the discussed prior art teachings is the plain feature that the grates are sloped downwardly and outwardly from the coal feed line. This has been on the premise that unburned coal in the ash is minimized by gravity. The automatic stoker of Potts claims a grate inclined at an angle of from 14 to 22 degrees, with 18 degrees being the best mode.
According to the present invention, in contrast, the horizontal reorientation of the fire grate demonstrates a more efficient combustion of rice anthracite, then seen heretofore.
It is a principal object of the present invention to employ a substantially horizontal planar fire grate which minimizes fire falling into the underlying ash pan.
A further object of the invention is to burn with a deeper fire bed extracting greater heat from the coal and producing ashes of a more power-like consistency.
Another object of the invention is to induce combustion flames across the internal heat surface of the furnace, thus providing more sensible heat to the area being warmed.
Another object of the modified fire grate component of the present invention is to cause generally vertical flaming from the grate which thus protects the glass fire door from overheating and microcrazing of the glass.
A further object of the invention is to array the infed coal more uniformly across the fire grate so as to cause it to burn more efficiently and to markedly reduce uncombusted coal falling off the grate as part of the ash pan.
Other objects and advantages and features of the invention will be apparent to those skilled in the art from the following description taken in conjunction with the accompanying drawings.
The invention described herein may be summarized as being an automatic coal stoker having a rear mounted coal hopper adapted to receive rice-sized anthracite. At the hopper bottom, is an enshrouded pusher assembly that provides for intermittent reciprocating action, whereby the rice coal is compacted into a restricted passage, forming a compacted strip form as it moves onto the fire grate (repetitively), have sidewall rails adapted for coal retention on the fire grate which is situated over a forced air feed box. The compacted coal is pushed onto the fire grate which itself is aligned in a substantially horizontal position. The intermittent sliding of compacted coal strips will maximize coal combustion and minimize the minor amount of unburned coal, which is pushed off the grate distal end, for disposal along with the coal ash.
Accordingly, there is provided a coal stoker including a hopper with the lower forward passage, a base box forming a coal ash pan, an elongate planar member having a first inclined section supporting a pusher assembly suited for intermittent feed of compacted coal to the furnace, and an elongate second section comprising a fire grate, either integral or being in modules, both having a multiplicity of perforations therein, which grate also forms the top of a forced air box, the improvement comprising:
Upon positioning, the fire grate section is in a substantially horizontal position throughout its linear length by straddling between the inclined feed first section and the downstream drop off point for coal ash and uncombusted coal.